When a judge acquitted a white St. Louis police officer in September 2017 for fatally shooting a young black man, the city’s police braced for massive protests. But St. Louis Metropolitan Police Department Officer Dustin Boone wasn’t just prepared for the unrest — he was pumped.

“It’s gonna get IGNORANT tonight!!” he texted on Sept. 15, 2017, the day of the verdict. “It’s gonna be a lot of fun beating the hell out of these s---heads once the sun goes down and nobody can tell us apart!!!!”

Two days later, prosecutors say, that’s exactly what Boone did to one black protester. Boone, 35, and two other officers, Randy Hays, 31, and Christopher Myers, 27, threw a man to the ground and viciously kicked him and beat him with a riot baton, even though he was complying with their instructions.

But the three police officers had no idea that the man was a 22-year police veteran working undercover, whom they beat so badly that he couldn’t eat and lost 20 pounds. On Thursday, a federal grand jury indicted the three officers in the assault. They also indicted the men and another officer, Bailey Colletta, 25, for the attack. Prosecutors released text messages showing the officers bragging about assaulting protesters, with Hays even noting that “going rogue does feel good.”

To protest leaders, the federal charges are a welcome measure of justice — but also a sign of how far St. Louis still has to go four years after the Ferguson protests helped galvanize a national movement for police accountability.

“If it was not a police officer — and particularly a black police officer — who was the victim of this assault, would we be at this juncture?” the Rev. Darryl Gray, one of the protest organizers, said to The Washington Post. “We’ve had several incidents of protesters and activists being the victims of excessive use of force and police abusing their authority without ever seeing charges like this.”

The 2017 protests centered on the case of officer Jason Stockley, who had killed 24-year-old Anthony Lamar Smith in December 2011 after chasing him following an alleged drug buy. Stockley had an unauthorized, personal AK-47 on the scene and was recorded on a dash cam during the chase saying he was “going to kill” Smith. Moments later, after Smith crashed, Stockley fired five fatal shots into his car.

In 2016, local prosecutors charged Stockley with first-degree murder and alleged the officer planted a revolver in Smith’s car after the killing. When a judge acquitted him on Sept. 15, 2017, activists who had emerged from the Ferguson protests planned mass demonstrations around St. Louis.

Gray said he expected police to act much as they did during Ferguson, when heavily militarized officers stormed protesters, drawing national condemnation from civil rights activists. “We knew that from 2014, the police culture had not changed,” he said. “We knew it wasn’t going to be pretty.”

In fact, texts from Boone, Hays and Myers suggest those officers were explicitly looking forward to violently attacking protesters. The day the verdict was released, Myers suggested they “whoop some ass.” Boone boasted about how he would beat “people up when they don’t act right,” and “just grab” protesters and “toss them around.”

Asked how he was faring during the demonstrations two days after the verdict, Boone responded, “A lot of cops getting hurt, but it’s still a blast beating people that deserve it. . . . I’m enjoying every night.”

That same day, Boone, Hays and Myers encountered a man identified as L.H. in federal documents. According to the St. Louis Post-Dispatch, he was Luther Hall, a veteran city police officer working undercover during the demonstrations. Though he made no effort to resist, the three officers brutally beat Hall, who was left with a two-centimeter hole above his lip, an injured tailbone and back injuries that required surgery; he still hasn’t recovered enough to return to work, the Post-Dispatch reported.

In the weeks afterward, prosecutors say, the three police officers gave false statements about the arrest and even directly contacted Hall to try to dissuade him from pursuing charges. Myers also destroyed Hall’s cellphone, prosecutors say. Colletta, who was romantically involved with Hays, also lied to investigators about the assault, according to the indictment.

Boone, Hays and Myers face charges of depriving Hall of his constitutional rights and conspiring to obstruct justice. Myers also faces a charge of destroying evidence, and Colletta is charged with obstructing, influencing or impeding a grand jury.

The four officers are being represented by police union lawyers who declined to comment to the Post-Dispatch. Jeff Roorda, the union’s head, told the Post-Dispatch, “We encourage elected officials, the media and the public to allow them their day in court without speculation about their guilt or innocence.”

“Those officers are excited and proud of beating up protesters and folks exercising their rights,” Franks told The Washington Post of the new text messages. “My case was in 2014 and now this is from 2017. This culture hasn’t changed.”

Franks said he plans to introduce legislation to more tightly restrict use of force by police and to offer more legal protections to protesters. But he also urged prosecutors to look deeper into the 2017 protests, which led to dozens of arrests — including a Post-Dispatch journalist who has filed one of at least 14 lawsuits over the police response.

“We need to hold everyone accountable, not just these officers,” Franks said. “There were more officers involved. We have higher-ups who were involved.”

As dark a picture as the indictments paint of police actions during the protests, Gray sees hope in the story being revealed.

“Maybe this police officer getting beat up by three of his own, who deliberately went out to hurt someone who was compliant and not resisting, maybe this is what is needed in this country and this city and this region to finally say, ‘We have not gone far enough to hold police accountable,’ ” Gray said.

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